Uterine myomas, often called uterine fibroids or leiomyomas, are common, non-cancerous growths that develop within the muscular wall of the uterus. Originating from the smooth muscle tissue, they vary widely in size, from microscopic to masses large enough to fill the abdominal cavity. Myomas are the most frequent benign tumors found in the female reproductive system, prevalent among women of childbearing age. Estimates suggest up to 70% of women may develop them by age 50. While many individuals experience no symptoms, these growths can lead to significant health issues for others.
Defining Uterine Myomas and Their Types
Uterine myomas arise from the myometrium, the thick, middle layer of the uterine wall composed primarily of smooth muscle cells. A single cell in this layer divides repeatedly, forming a firm, rubbery mass distinct from the surrounding tissue. Although they are tumors, myomas are benign neoplasms and are almost never associated with an increased risk of uterine cancer.
Myoma classification is based on its specific location within the uterus, which directly impacts the symptoms it may cause. The three primary classifications are submucosal, intramural, and subserosal.
Submucosal myomas grow just beneath the inner lining and project into the uterine cavity. This type is the most likely to cause heavy bleeding. Intramural myomas are the most common type, developing entirely within the wall of the uterus and causing the organ to expand. Subserosal myomas form on the outer surface of the uterus and can push outward into the pelvic or abdominal cavity. These growths may sometimes be attached by a stalk, known as a pedunculated myoma.
Identifying the Symptoms of Myomas
Symptoms are most often linked to the myoma’s size and location. Abnormal uterine bleeding is the most common manifestation, characterized by heavy or prolonged menstrual periods (menorrhagia). This excessive blood loss can lead to secondary problems, such as chronic fatigue and anemia resulting from a reduction in red blood cells.
Many individuals report significant pelvic pressure and discomfort, often described as a feeling of fullness or chronic bloating in the lower abdomen. This pressure relates directly to the physical bulk of the myomas, especially as they grow larger and distort the shape of the uterus. The location of the growths can also cause pain during sexual intercourse or chronic lower back pain.
Secondary symptoms arise when myomas press against adjacent organs. For instance, a large subserosal myoma pushing on the bladder can lead to frequent urination, urgency, or difficulty emptying the bladder completely. Growths pressing on the rectum can interfere with normal bowel function, resulting in chronic constipation.
Key Risk Factors and Underlying Causes
The precise reason myomas develop is not fully understood, but their growth links closely to hormonal, genetic, and demographic factors. Hormonal influence is a primary driver, as myomas contain a higher concentration of receptors for estrogen and progesterone than normal uterine tissue. Because these hormones stimulate the uterine lining, they also promote myoma growth. Consequently, myomas typically grow during the reproductive years and often shrink naturally after menopause when hormone levels decline.
Genetic and familial predisposition plays a substantial role; the risk of developing myomas is approximately three times higher if a mother or sister has had them. Research indicates that myomas frequently possess specific genetic mutations, such as in the MED12 gene, suggesting an inherent abnormality in the uterine muscle cells is involved in their formation. Myomas are also more common in women in their late 30s and 40s.
Specific populations, particularly Black women, have a higher prevalence and often experience myomas at a younger age, with greater severity and larger growths. Other risk factors include:
- Onset of menstruation at an early age, which increases lifetime exposure to reproductive hormones.
- Obesity, as excess body fat can lead to higher circulating levels of estrogen.
- A diet high in red meat and low in fruits and vegetables.
- A lack of vitamin D.
Diagnosis and Treatment Options
Diagnosis typically begins with a pelvic examination, where a healthcare provider may detect an enlarged or irregularly shaped uterus. The most common initial imaging tool is an ultrasound, which uses sound waves (transabdominal or transvaginal) to create images of the uterus, confirming the presence, size, and location of the growths. For complex cases or when surgical planning is required, a Magnetic Resonance Imaging (MRI) scan provides a detailed map of the myomas within the uterine wall.
The approach to treatment is highly individualized, depending on the severity of symptoms, the myoma’s location, the patient’s age, and the desire to maintain fertility. For individuals who are asymptomatic or have mild symptoms, watchful waiting is often recommended, as myomas are benign and may not require immediate intervention. This involves monitoring the growths over time.
Medical management focuses on alleviating symptoms, especially heavy bleeding, through hormonal therapies. Birth control pills or hormonal intrauterine devices (IUDs) can help control menstrual flow. Gonadotropin-releasing hormone (GnRH) agonists are another option; they temporarily reduce the size of myomas by inducing a reversible menopausal state. GnRH agonists are often used before surgery or for those approaching natural menopause.
For persistent or severe symptoms, minimally invasive or surgical interventions are considered. Uterine Fibroid Embolization (UFE) is a non-surgical, minimally invasive procedure where small particles are injected into the arteries supplying the myomas, blocking their blood flow and causing them to shrink. UFE preserves the uterus and is an option for women who wish to avoid major surgery.
Surgical treatment includes two main options: myomectomy and hysterectomy. Myomectomy is the surgical removal of the myomas while leaving the uterus intact, making it the preferred choice for those who desire future pregnancy. The procedure can be performed:
- Abdominally
- Laparoscopically
- Robotically
- Hysteroscopically
Hysterectomy, the complete surgical removal of the uterus, is the definitive cure for myomas, as it eliminates the possibility of future recurrence. This option is reserved for individuals with severe symptoms who have completed childbearing or for whom other treatments have been ineffective.